Control system for a hydraulic servomotor

Abstract

A control system for a hydraulic servomotor ( 13 ) is disclosed. The control system comprises an electro hydraulic actuator ( 2 ) comprising a number of valves ( 9, 10, 11, 12, 18 ) for controlling fluid flows, a main control module ( 1 ), and one or more connectors. The control system further comprises at least one extension control module ( 3 ) comprising one or more connectors. Finally, the control system comprises means ( 6 ) for communicating signals between the main control module ( 1 ) and each of the extension control module(s) ( 3 ). Since the main control module ( 1 ) and the extension control module(s) ( 3 ) are able to communicate signals, it is possible to provide signals to/from the main control module ( 1 ) via an extension module ( 3 ), thereby in effect providing additional connectors to the main control module ( 1 ). Thereby the main control module ( 1 ) may be able to perform additional functions as compared to similar prior art control modules.

1. A control system for a hydraulic servomotor, the control system comprising:
 an electro hydraulic actuator comprising a number of valves for controlling fluid and a main control module adapted to supply control signals to at least some of said valves, thereby controlling the fluid, and comprising one or more connectors for receiving and/or transmitting signals, 
 at least one extension control module comprising one or more connectors for receiving and/or transmitting signals, and 
 means for communicating signals between the main control module and each of the extension control module(s) via said connectors, 
 wherein the main control module and the extension control module(s) form a master/slave configuration in which the main control module acts as master module and the extension control module(s) act(s) as slave module(s). 
 
   
   
     2. The control system according to  claim 1 , wherein at least one extension control module forms part of a second electro hydraulic actuator. 
   
   
     3. The control system according to  claim 2 , wherein the extension control module(s) forming part of a second electro hydraulic actuator is/are adapted to provide redundant control of the hydraulic servomotor. 
   
   
     4. The control system according to  claim 1 , wherein at least one extension control module is identical to the main control module. 
   
   
     5. The control system according to  claim 1 , wherein the means for communicating signals comprises a bus connection. 
   
   
     6. The control system according to  claim 1 , wherein the hydraulic servomotor comprises a cylinder and a double acting piston slidably mounted in the cylinder and defining a first chamber and a second chamber in the cylinder, said piston being slidably movable in a first direction in response to a supply of fluid to the first chamber, and in an opposite second direction in response to a supply of fluid to the second chamber, said fluid flows being controlled by means of the valves. 
   
   
     7. The control system according to  claim 1 , wherein the hydraulic actuator comprises four valves arranged in a bridge circuit, the hydraulic servomotor being arranged between diagonals of the bridge circuit. 
   
   
     8. The control system according to  claim 7 , wherein at least one of the valves is an electrically operable valve. 
   
   
     9. The control system according to  claim 8 , wherein at least one of the valves is normally closed in a de-energized state. 
   
   
     10. The control system according to  claim 7 , further comprising at least one additional valve arranged in parallel to one of the valves forming the bridge circuit. 
   
   
     11. The control system according to  claim 7 , further comprising at least four additional valves arranged in at least one additional bridge circuit, said additional bridge circuit being arranged in parallel with the first bridge circuit. 
   
   
     12. The control system according to  claim 11 , wherein the hydraulic actuator comprises at least one additional hydraulic servomotor being arranged between diagonals of a bridge circuit. 
   
   
     13. The control system according to  claim 7 , wherein at least one valve is driven by a pulse train signal. 
   
   
     14. The control system according to  claim 7 , wherein the valves are controlled by means of a closed loop control of the hydraulic servomotor. 
   
   
     15. The control system according to  claim 14 , further comprising at least one sensor, said sensor(s) being adapted to provide an input signal to the closed loop control. 
   
   
     16. Use of a control system according to  claim 1  in a hydro-mechanical transmission (HMT). 
   
   
     17. Use of a control system according to  claim 1  in an electro hydraulic steering application.